Abstract: Fluorescence data obtained by laser excitation at 266 nm were used for the first time to determine fluorescence properties of household and chicken farm discharges. Two fluorescence indices were applied: a modified humification index (HIX) and a new one, as tyrosine:tryptophan ratio (Tyr/Trp). HIX described very well the degree of contamination of the water system, while Tyr/Trp was useful in discriminating between the types of contaminants-household or chicken farms discharges. Results suggest that chicken farm wastes pollution could leave a specific fluorescence signature, when found in rivers, making possible their identification from the background fluorescence of the river waters.